Liquid crystalline blends, device thereof and method thereof

Abstract

The invention provides liquid crystalline blends, a device such as a photovoltaic cell using the blend and method thereof. A liquid crystalline blend comprises at least an electron donor and at least an electron acceptor with a weight or molar ratio in the range of from about 1:20 to about 20:1. Another liquid crystalline blend comprises at least an electron donor and at least an electron acceptor, wherein the electron donor, the electron acceptor, or both is (are) halo-substituted such as F-substituted. The donor or the electron acceptor can be excited by an electromagnetic radiation such as solar light to induce electron transfer between the donor and the acceptor. The photovoltaic cell is improved in that favorable molecular arrangement in the blend gives more interfaces between the donor and the acceptor and thus a viable path for dissociation and electrons and / or holes; as well as larger light-harvesting area toward the coming light.

Description

[0001]This application claims the priority of the U.S. provisional application with the application number of 61 / 107,386, which was filed on Oct. 22, 2008.BACKGROUND OF THE INVENTION[0002]The present invention is related to liquid crystalline blends, devices thereof and methods thereof. It finds particular application in conjunction with an organic semiconducting material, a photovoltaic device such as a bulk heterojunction photovoltaic cell, a solar cell, a homeotropically aligned blend thin film, a liquid crystalline blend thin film, a photo-sensitive electric resistor, and an organic light emitting device; and will be described with particular reference thereto. However, it is to be appreciated that the present exemplary embodiment is also amenable to other like applications.[0003]In the long term, solar energy is the only source of renewable energy that has the capacity to fill humanity's technological needs. A grand challenge is to convert solar energy into green electric energ...

AI Technical Summary

Benefits of technology

The invention provides a liquid crystalline blend that includes an electron donor and an electron acceptor, which can be excited by electromagnetic radiation to induce electron transfer between them. The blend can be used in various materials and devices such as photovoltaic cells, solar cells, and organic light emitting devices. The technical effect of the invention is to provide a new way to design materials that can improve the performance of photovoltaic cells and other electronic devices.

Problems solved by technology

A grand challenge is to convert solar energy into green electric energy in an inexpensive and efficient way.

The crystalline silicon photovoltaic cells, though efficient, appear to be too expensive to compete with primary fossil energy.

Currently widely used OPV materials, e.g. Cu phthalocyanine, suffer from the scattering of electron / exciton between small crystal grain boundaries in which random arrangement of molecules results in poor charge mobility.

The attainment of large-area single crystals or desired molecular arrangement of either inorganic (e.g. silicon) or organic molecules is difficult and costly to process although a crystalline phase has superior properties compared to the same material in an amorphous phase.

A challenge for OPV, with the possibility of very significant cost reduction, is to make them in desired macroscopic order to improve charge transportation etc.

So, only the excitons close to the donor-acceptor interface in a donor and acceptor bilayer photovoltaic cell can contribute to the photocurrent, which dramatically limits photovoltaic performance.

However, one challenge that remains for OPV technology, with the possibility of very significant cost reduction, is to make them in desired macroscopic order to improve charge transportation.

However, to date there is no report on the alignment of discotic LC (such as porphyrin)-fullerene blend or fluorinated LC-fullerene blend, particularly when the ratio between the two is in the range of 1:20 to 20:1.

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